The present invention relates generally to video mixer apparatus capable of mixing a plurality of video pictures to create a special video picture, and more particularly to an improved video mixer apparatus that mixes video pictures, as appropriate, input via three or more input channels to create a special video picture.
Today, in many music concerts, discotheque clubs and the like, video pictures, not only still pictures and animated pictures, edited by a VJ (acronym for a Visual Jockey) or other picture artist having a good artistic sense are visually displayed to music pieces played by a band or DJ (Disk Jockey), so as to impart comprehensive effects to an entire place in question in accordance with musical scenes. It has been known to use a video mixer apparatus (also known as a video switcher apparatus) in such video picture editing by a VJ or the like. Typical example of the conventional video switcher apparatus is arranged to synthesize a plurality of video picture signals input from a plurality of video tape recorders and/or cameras to thereby create a special video picture. In addition to thus creating a special video picture by synthesizing a plurality of video picture signals, the conventional video switcher can create a video picture imparted with a predetermined effect, such as an overlap, wipe or keying. However, the conventional video mixer apparatus can only additively synthesize video picture signals receive from two input channels. Namely, although the conventional video mixer apparatus can receive video picture signals via a plurality of (e.g., four) input channels, it selects, as appropriate, the video picture signals received via just two of the input channels and then additively synthesizes the video picture signals of the thus-selected two input channels.
Because the conventional video mixer apparatus is designed to additively synthesize video picture signals received via only two selected input channels as noted above, the single video mixer apparatus can not, by itself, mix input video picture signals of three or more input channels to create a special video picture. Thus, for mixing video picture signals received via three or more input channels, it has heretofore been necessary to connect a plurality of such video mixer apparatus, which would, however, disadvantageously result in an increased overall size or reduced compactness of the apparatus. Further, when video picture signals received via three or more channels are to be simultaneously mixed together to create a special video picture, it has been conventional to perform the signal mixing step by step by appropriately manipulating the plurality of video mixer apparatus. However, performing the mixing by quickly and appropriately combining video picture signals of desired channels, selected from among the three or more channels, would require a great amount of time and labor and encounter extremely great difficulty.
Further, in the case where video picture signals received via two input channels are to be additively synthesized via the conventional video mixer apparatus, the user can vary a synthesis ratio between the video picture signals of the channels using a so-called T-Bar (Take-Bar). But, for variation in the synthesis ratio between the video picture signals received via the two input channels using the T-Bar like this, it has been only possible to set the synthesis ratio such that respective proportions of the video picture signals received via the two input channels always sum to 100%, e.g. with the video picture signal of the first input channel being set to 32% of a maximum amount for the first input channel and the video picture signal of the second input channel being set to 68% of a maximum amount for the second input channel. Namely, the use of the T-Bar alone can not set a desired synthesis ratio between the video picture signals received via the two input channels (e.g., 100% of the first-channel maximum amount to the video picture signal of the first input channel and 15% of the second-channel maximum amount to the video picture signal of the second input channel, or 30% of the first-channel maximum amount to the video picture signal of the first input channel and 20% of the second input channel to the video picture signal of the second input channel). Thus, when the video picture signals received via the two input channels are to be mixed at a desired synthesis ratio, extremely complicated manipulations must be performed, which tend to cause great inconveniences in quick video picture editing.